Australian marathon swimmer Chloe McCardel, who has crossed the English Channel multiple times, said Thursday she had made her first and only attempt from the island nation to the Florida Keys without a shark cage.

Not even in a full-body suit a la perennial swimming candidate Diana Nyad?

"Negative -- not coming back here for swimming, but I would love to do more tourist activities," McCardel, 28, said aboard the charter yacht Mathilda, which carried her to a Stock Island marina in the wee hours of Thursday morning.

Wearing a simple suit, cap and goggles, McCardel made an organized attempt at crossing the ocean from Havana, Cuba, to the Keys early Wednesday, 9.5 months in the making and billed as a fundraiser for cancer charities.

But McCardel was pulled from the water by her support team at about 11 hours, after diving in feet first from Cuba, due to a relentless attack by box jellyfish that left her debilitated and unable to do much but swim in circles.

"I was in searing pain; my hips were locked," McCardel said. "I felt paralyzed from the waist down. I couldn't kick or get forward movement."

Speaking to reporters Thursday afternoon at the Key West Harbour Yacht Club, McCardel said none of her marathon swimming events prepared her for the painful reality of jellyfish stings.

"I've been stung by a Portuguese man-of-war, but you can swim through that stuff," McCardel said. "This was something I've never experienced and hope I never will again. I wouldn't wish it on my worst enemy."

Apparently, the 103-mile swim, estimated to take a maximum of 2.5 days, cannot be done under "English Channel rules," meaning no wet suit, no touching a boat or holding onto anything the entire trip.

"What I went through kind of magnified and exemplified that it's not possible to swim those conditions in these waters," said McCardel.

Nyad, 63, who recently said she will make her fifth attempt at the Cuba-to-Keys swim, tweeted a supportive shout-out to McCardel.

"It's a tough night for Chloe McCardel, a superior swimmer and an exemplary spirit," wrote Nyad, who in 1972 swam 102.5 miles from North Bimini, Bahamas, to Juno Beach, Fla.

Despite a full body suit, which included gloves, Nyad in August was pulled out by her crew after 60 hours in the water.

Her lips were severely swollen, as she showed at Higgs Beach, where she ceremoniously swam into shore wearing a simple swimsuit, walking onto the sand with arms raised for the cameras.

The only person to ever make the swim is Susie Maroney, another Australian, who made it at age 22 in 1997, but with the benefit of a shark cage.

McCardel said Thursday that her attempt raised about $65,000 for cancer charities, via www.chloemccardel.com.

In the world of endurance swimming, McCardel is a pro who has completed six solo crossings of the 21-mile English Channel and two solo double crossings.

In September 2009, she swam 24 hours and 50 minutes in a double channel crossing attempt. A year later, she swam the double crossing in 21 hours, 48 minutes.

McCardel, from Melbourne, started swimming at age 10 and has been a vegetarian since she was 11, her website profile says.

While her record, timewise, is 25 hours in the water, McCardel had felt prepared for a 60-hour open swim.

The first several hours were actually great, she said. She saw a pod of dolphins, and felt strong mentally and physically.

"I was on cloud nine," said McCardel.

But the jellyfish stings began once the sun went down. The swimmer was stuck in the water, unable to see what was coming at her.

She asked for ointment from her crew and managed to put some on in the water, but it didn't assuage the pain, which she described as "fireworks explosions" through her body.

"I could feel the tentacles," she said. "It was like the floodgates were open."

Advisers had told McCardel that June was the best month for the swim, since jellyfish are supposedly spread out more in the Florida Straits.

"Either I was super unlucky or the information I got was wrong, or they just happened to be concentrated in the area I was swimming," McCardel said.

While Cuba to the Keys was a major goal, McCardel had a what's-done-is-done demeanor on Thursday.

She got choked up a little when describing in detail being essentially trapped in the darkness taking in the jellyfish stings, but mostly had a toothpaste-white grin and modest nature with the various reporters and cameramen during an informal press conference.

She said she was taking a nice, long time off from marathon swims.

"If I'd known exactly what would happen, I wouldn't have gone in with what I was wearing," McCardel said. "I would have chosen to swim elsewhere."